The invention pertains to a windshield wiper system.
German specification AS No. 2 102 033 shows a windshield wiper system for motor vehicles, in which two windshield wipers, each mounted on a separate wiper shaft, can be driven to and fro between an inner reversing position and an outer reversing position by a common motor. The two windshield wipers run through one wiping cycle in opposite directions. In their outer reversing position the two wipers lie in opposite corners of the window pane to be cleaned approximately parallel to the bottom rim. The two wipers have wiping areas which overlap in the center of the window pane, so that there is a common wiping area. Collision of the two windshield wipers in the common wiping area must be prevented. To achieve this, each windshield wiper is driven via a crossed crank-rocker mechanism which consists of a motor crank, a rocker arm firmly connected with the wiper shaft and coupling rod. The coupling rod is articulated both onto the motor crank and onto the rocker arm. The two crossed crank-rocker mechanisms are arranged such that for one windshield wiper the forward motion is more rapid than the return motion and for the other windshield wiper the return motion is faster than the forward motion. This provides that one windshield wiper reaches the common wiping area only after the other has already left it.
In a windshield wiper system according to the German specification DE-AS No. 1 268 505 two windshield wipers are also driven by one motor in opposite directions between an inner and an outer reversing position. The two windshield wipers lie parallel to each other and to the bottom rim of the window pane in their inner reversing position. In this position they overlap in their longitudinal direction for a certain distance, so that a substantially triangular common wiping area is provided in which collision of the two windshield wipers must be prevented. The gearing members are therefore used such that upon leaving the inner reversing position the upper or first windshield wiper is at first driven more rapidly than the lower or second one, but then the first one becomes slower and the second one faster, so that both windshield wipers reach their outer reversing positions at the same time. In the return run the second windshield wiper is at first driven faster than the first one. However both windshield wipers reach the inner reversing position at the same time again, because during the return run the first windshield wiper is subsequently driven faster than the second one. In a windshield wiper system of this kind only a small common wiping area for the two wipers is possible, so that in the center of the window pane a large wedge-shaped section is left which is not wiped at all.
A so-called double windshield wiper system is also known with two windshield wipers and two motors, of which each one drives one windshield wiper. There is also a common wiping area in this windshield wiper system. However, the two windshield wipers are moved in the same direction.